The lecturer agrees with the passage that internal-combustion engines do bring about problems in the sense that petroleum is not infinite and the burning cause pollution. However, the lecturer casts doubt on the feasibility of hydrogen-based fuel engine for the following reasons.
First, contrary to the belief in the passage that hydrogen is readily available because it presents in natural gas and even water, the professor says the hydrogen cannot be used directly, in stead, the hydrogen must be purified. In fact, it is technically very difficult to purify the hydrogen and store them because extremely cold temperature is required during this process.
Second, the professor refutes the passage in the sense that hydrogen engine do not cause pollution. According to the lecture, the production of purified hydrogen needs a lot of energy and the energy has to come from the burning of coal and oil. Therefore, though the burning of hydrogen fuel will not cause pollution, the factories which produce hydrogen will do.
Finally, while the passage says that hydrogen-based fuel-cell will cost less, the professor disagrees. She says that the fuel cell must be made of the very expensive metal, platinum, to allow the chemical reactions to occur. Therefore the cost of fuel-cell engine is not necessarily less than the internal-combustion engine.
(最后一段另一个版本)The professor also disagrees with the opinion made in the passage that hydrogen-based fuel-cell engine is twice as efficient as internal-combustion engine, thus costing much less. She says that platinum, a rare and expensive metal, is required to allow the chemical reaction that produce energy to take place, so the cost might not be necessarily scaled down.)
G考了5分的作文,托福综合写作都是得FAIR,实在不明白到底差在哪里。。。欢迎大家提出宝贵建议,小妹感激不尽~~